Technological advances allow the manipulation of extremely small units of matter, even individual atoms, opening up the possibility of macrofabrication technologies. Such technologies could be used to design nano and micro-scale machines, or to accurately control individual elements in larger materials or machines. Practical realization of these technologies is blocked by the inability to adapt experimental and small scale techniques to the larger scales required of industrial production. Conventional materials production is a linear process. Doubling the amount of material created requires twice the production time. Linear scaling of production is a critical problem if the goal is to create useful, i.e. macroscopic, quantities of microscopic building blocks with sophisticated internal structures.
Exponential growth is the most elegant and effective solution to the problem, as demonstrated by biological systems, in which a single cell generates offspring which themselves can build more copies. A single cell containing the necessary information can also divide and develop into a living organism, demonstrating that large, complex systems can be built and operated from self-reproducing units. While nature teems with organisms that readily reproduce, no one has yet succeeded in making an artificial material that can repeatedly copy itself. Making a material which self-replicates presents not only a significant scientific challenge but also the potential for applications which bridge the microscopic and macroscopic worlds. Self-replication leads to exponential growth providing a practical means to scale up production of components for nanomachines and larger scale more functionally complex assemblies. Demonstrating self-replication and developing the science behind it therefore represents an important step for nanotechnology and for enabling the practical development of the technology.